| In the past 30 years,with the continuous progress of science and technology,urban construction has been expanding,which has promoted the rapid development of the economy,it has brought about serious problems such as environmental pollution.In particular,the development of industries such as mining and metal smelting has caused heavy metal ions to flow into soil,water and the atmosphere.Due to the everexpanding and spreading trend of pollution area,it poses a threat to food security,human living environment safety,drinking water safety,ecological environment security and sustainable development of resources.Therefore,it is imperative to fully implement the solidification stabilization technology for heavy metal contaminated soil,which is conducive to the rational use of soil resources and the protection of the ecological environment.Based on the major project of technological innovation in Hubei Province,“Key Technologies Development and Application of Soil Solidification/Stabilization Rehabilitation for Compound Heavy Metal Polluted Soil Based on Alkaline Industrial Waste”,in this paper,Industrial waste residue was used to solidify and stabilize heavy metals,and industrial waste residue and cement were used as curing agents,which promotes the resource utilization of industrial waste residue and is conducive to environmental protection.By studying the variation of leaching concentration,mechanical properties and microstructural properties of cured solids under different influencing factors,The following conclusions are drawn:(1)The activity of industrial waste can be preliminarily judged by its pH,element composition and content,and XRD characterization.All the four industrial wastes are alkaline,and free hydroxyl radicals can form co-precipitation with cationic heavy metals.It is concluded that the activities of electric furnace slag,converter slag and water quenched blast furnace slag are stronger,while the activity of bottom slag is the weakest.(2)By analyzing the effects of curing age and industrial waste mixing amount on the unconfined compressive strength of solidified heavy metal contaminated soil,it is concluded that The unconfined compressive strength of the solidified soil is positively correlated with the addition of industrial waste and the growth of curing age.Among them,the unconfined compressive strength of water quenched blast furnace slag is the best.However,the strength of the four industrial wastes can meet the soil remediation standards of European and American countries when the addition is 15% and the curing time is 7 days.(3)Based on the leaching toxicity test of solid waste,the effects of curing age and the mixing amount of industrial waste on the leaching concentration of solidified solids were analyzed.It is concluded that the leaching concentration of heavy metal contaminated soil solidified by industrial waste decreases with the increase of curing age and alkaline residue mixing amount.The solidification effect of chromium contaminated soil solidified by electric furnace slag,converter slag and water quenched blast furnace slag is better than that solidified by bottom slag.Moreover,the pH value of leaching solution has a great influence on the adsorption of heavy metal ions by industrial waste.With the increase of leaching solution pH value,the adsorption capacity of industrial waste to arsenic and lead ions in contaminated soil increases.(4)The microstructural characteristics of heavy metal contaminated soil solidified by industrial waste under different curing ages and different concentrations of heavy metals were compared and analyzed.It is concluded that there are a lot of hydration products formed in the process of solidification of heavy metal contaminated soil by industrial waste,and the number and size of pore gradually decrease and the structure becomes dense with the increase of curing age.converter slag solidifies the soil contaminated by heavy metals best,and the soil becomes dense by filling pore. |
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